linux-kernel - [PATCH v10 01/25] mm: introduce CONFIG_SPECULATIVE_PAGE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1523975611-15978-2-git-send-email-ldufour@linux.vnet.ibm.com>
Date:   Tue, 17 Apr 2018 16:33:07 +0200
From:   Laurent Dufour <ldufour@...ux.vnet.ibm.com>
To:     akpm@...ux-foundation.org, mhocko@...nel.org, peterz@...radead.org,
        kirill@...temov.name, ak@...ux.intel.com, dave@...olabs.net,
        jack@...e.cz, Matthew Wilcox <willy@...radead.org>,
        benh@...nel.crashing.org, mpe@...erman.id.au, paulus@...ba.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, hpa@...or.com,
        Will Deacon <will.deacon@....com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        kemi.wang@...el.com, sergey.senozhatsky.work@...il.com,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        David Rientjes <rientjes@...gle.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Ganesh Mahendran <opensource.ganesh@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        haren@...ux.vnet.ibm.com, khandual@...ux.vnet.ibm.com,
        npiggin@...il.com, bsingharora@...il.com,
        paulmck@...ux.vnet.ibm.com, Tim Chen <tim.c.chen@...ux.intel.com>,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: [PATCH v10 01/25] mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT

This configuration variable will be used to build the code needed to
handle speculative page fault.

By default it is turned off, and activated depending on architecture
support, SMP and MMU.

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Suggested-by: David Rientjes <rientjes@...gle.com>
Signed-off-by: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
---
 mm/Kconfig | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/mm/Kconfig b/mm/Kconfig
index d5004d82a1d6..5484dca11199 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -752,3 +752,25 @@ config GUP_BENCHMARK
 	  performance of get_user_pages_fast().
 
 	  See tools/testing/selftests/vm/gup_benchmark.c
+
+config ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
+       def_bool n
+
+config SPECULATIVE_PAGE_FAULT
+       bool "Speculative page faults"
+       default y
+       depends on ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
+       depends on MMU && SMP
+       help
+         Try to handle user space page faults without holding the mmap_sem.
+
+	 This should allow better concurrency for massively threaded process
+	 since the page fault handler will not wait for other threads memory
+	 layout change to be done, assuming that this change is done in another
+	 part of the process's memory space. This type of page fault is named
+	 speculative page fault.
+
+	 If the speculative page fault fails because of a concurrency is
+	 detected or because underlying PMD or PTE tables are not yet
+	 allocating, it is failing its processing and a classic page fault
+	 is then tried.
-- 
2.7.4